Sodium Thiosulfate is a white translucent crystals or powder that is common as the pentahydrate form; melting at 48 C; readily soluble in water and oil of turpentine; aqueous solution is slightly alkaline which decompose to sulfate and sulfide in the air. It is a moderate reducing agent. It is a source of thiosulfate ion (S2O3-2) (dissolves silver salts). Its major use is as a fixing agent in photography for developing film and the extracting silver from ore. It is used in chrome-tanning leather and in chemical manufacture as a source of sulfide ion. It is also used in paper, textile and gas purification. Sodium Thiosulfate Pentahydrate FCC WC Code: 19-125-02 Sales Specification Appearance: Solid Assay: 99.00 % Sodium Thiosulfate (Na2S2O3) : 100.50 % Lead: 2 mg/kg Selenium: 0.003 % Water: 32.00 %- 37.00 % Sulfate : Nil Sulfite : Nil Chloride: Nil pH of 10% solution: 6.0- 8.0 Iron: 0.002 % Packing 50 lb paper bag, 44 bags per pallet